The present invention relates to an image processing apparatus and, more specifically, to an image processing apparatus for processing a color image having secrecy or confidentiality.
In order to provide copy limit information to image data output from an image reader, the following method is normally adopted. That is, read prohibition information is added to image data when the image data is stored, and read access to the image data is limited unless a read enable condition presented by the read prohibition information is satisfied, thereby prohibiting the image data from being copied.
When an objective image is character information or a binary image, since only limited methods are available to output it, the conventional method is effective. However, in recent years, the mainstream of image data processing involve color image data having a large information volume, and there are various kinds of secret information. For this reason, the above-mentioned method is insufficient. For example, in the case of a color image whose color information (but not necessarily luminance information) it is desired to keep highly secret. Copying of the color image itself need not be completely prohibited. When copying of the color image itself is completely prohibited, availability and usefulness of the color image data are undesirably limited.